Avoid making conda a hard dependency (#1528)
Summary:
After some thoughts I believe we should keep conda an optional dependency because users might want to setup their own binary libraries and environment. We will first try installing binary libraries from conda, if failed, print a warning.
Fixes https://github.com/pytorch/benchmark/issues/1512.
Pull Request resolved: https://github.com/pytorch/benchmark/pull/1528
Reviewed By: janeyx99
Differential Revision: D44730545
Pulled By: xuzhao9
fbshipit-source-id: d932233a6946d07d716ad522c265cdcd43e750f2
